Two-layer liquid crystal panel having a polymer liquid crystal layer and equipment using the same

ABSTRACT

This invention relates to a two-layer display type of electronic equipment having a liquid crystal panel ( 1 ) and a background display portion ( 2 ) on a rear surface side thereof. The liquid crystal panel ( 1 ) has a main liquid crystal panel unit ( 10 ) formed by inserting a liquid crystal layer ( 13 ) between a first substrate ( 11 ) and a second substrate ( 15 ). The liquid crystal layer ( 13 ) is set to either a light-transmitting state or a light-scattering state by an electrical field that is applied to the liquid crystal. This liquid crystal panel ( 1 ) has a transparent layer ( 21 ) on the rear surface of the second substrate ( 15 ). If the refractive index of this transparent layer ( 21 ) is n 1 , the refractive index of the second substrate ( 15 ) in contact with the front side of this transparent layer is n 0 , and the refractive index of the air layer in contact with the rear side of the transparent layer ( 21 ) is n 2 , the following relationship is established: n 2 &lt;n 0 &lt;n 1 .

TECHNICAL FIELD

This invention relates to a liquid crystal panel and electronicequipment that uses such a liquid crystal panel.

BACKGROUND ART

In addition to various kinds of timepieces used as wristwatches, such asan analog timepiece displaying time by hands and a digital timepiecedisplaying time on a liquid crystal device, there has recently beendeveloped a two-layer display type of timepiece in which a liquidcrystal panel is superimposed on the surface of an analog timepiece, asdisclosed in, for example, Japanese Patent Publication No. 59-32755.With such a two-layer display type of timepiece, a digital time displaycan be superimposed on top of an analog time display, to make itvisible.

In the prior art, the display of a liquid crystal panel is often of acolor that has a low brightness, such as black, which means that thedisplay of the liquid crystal panel cannot be clearly seen if the analogdial plate is not of a color that has a high level of brightness, suchas white. This limits the design of such a dial plate.

That is why a display element having a polymer dispersed liquid crystallayer has been developed, as disclosed in International Publication No.WO94/23331. This liquid crystal layer has the property of beingtransparent when no electrical field is applied thereto, but it diffusesor scatters light when an electrical field is applied. Therefore, alight-scattering region to which an electrical field has been appliedappears to be white or gray, making it possible to display characters orthe like. Since the color of this display portion is white or gray, thatin itself is novel, and it means that the dial plate can be given acolor of a low level of brightness, such as black, blue, or red, andthus the dial plate can be freely designed.

In this case, light is scattered both forward and backward with respectto the direction in which the light is incident, within a region of thepolymer dispersed liquid crystal layer to which the electrical currentis applied. When a transmissive type of liquid crystal panel has beenfabricated by using this polymer dispersed liquid crystal layer, lightthat is scattered forward in the direction in which light is incident(hereinafter called “forward-scattered light”) strikes the eyes of theobserver, so this forward-scattered light can be used to provide aliquid crystal display that is white or gray.

A wristwatch or the like is required to be compact, lightweight, andenergy-thrifty, so it is often inevitable that a reflective liquidcrystal panel is used therefor. In such a case, light that is scatteredbackward with respect to the light-incident direction (hereinaftercalled “backward-scattered light”) strikes the eyes of the observer. Onthe other hand, forward-scattered light is directed along the directionin which light is incident, so it does not strike the eyes of theobserver.

Research performed by the present inventors has shown that, when areflective liquid crystal panel has been constructed by using a polymerdispersed liquid crystal layer, there is insufficient backward-scatteredlight, so that it is not possible to provide a suitable liquid crystaldisplay in white or gray if the forward-scattered light is notreflected. They have determined that this is particularly obvious whenthe quantity of backward-scattered light is greater than the quantity offorward-scattered light.

In this two-layer display type of timepiece, a member capable ofreflecting the forward-scattered light is simply the dial plate, whichis disposed forward of the liquid crystal panel in the direction inwhich light is incident. However, if this dial plate has a low level ofbrightness, insufficient light is reflected from the dial plate, andthus the display on the liquid crystal layer can not be seen. To counterthis, there is no option but to make the dial plate a reflectivesurface, but this has the effect of further limiting the design of thedial plate.

When a structure is used that causes the forward-scattered light to bereflected outside of the liquid crystal panel, the forward-scatteredlight diffuses within the space between the liquid crystal panel and thedial plate, generating a loss of light reflected off the dial plate andreturning towards the front side.

Furthermore, if forward-scattered light is reflected at a location farfrom the liquid crystal layer that generates the backward-scatteredlight, and if the line of sight of the viewer is at an angle to theperpendicular of the liquid crystal panel, there is a danger that aduplicated display will be caused by the pattern formed by backwardscattering and the pattern formed by forward scattering.

Such problems are not limited to a two-layer display type of timepiece;they form a common subject of technical concern in the design of othertypes of electronic equipment in which a background display portion isprovided behind a liquid crystal layer.

DISCLOSURE OF THE INVENTION

This invention was devised in the light of the above described problemsand has as an objective thereof the provision of a liquid crystal panelwhich makes it possible to expand the design limits of electronicequipment and which also makes the display thereof clearly visible.

A further objective of this invention is to provide a two-layer displaytype of electronic equipment which makes it possible to expand thedesign limits and which also makes the display thereof clearly visible.

A yet further objective of this invention is to provide electronicequipment which can reduce the occurrence of duplicated displays.

In order to solve the above described technical problems, there isprovided a liquid crystal panel in accordance with a first aspect ofthis invention, comprising:

a first substrate which is disposed on a side on which external light isincident and on which is formed at least one first electrode;

a second substrate which is disposed facing the first substrate and onwhich at least one second electrode is formed;

a liquid crystal layer which is inserted between opposing surfaces ofthe first and second substrates and which is set to one of alight-transmitting state and a light-scattering state, based on avoltage applied between the at least one first electrode and the atleast one second electrode; and

at least one transparent layer disposed forward of the liquid crystallayer in the light-incident direction;

wherein the at least one transparent layer is formed of a materialhaving a refractive index that differs from the refractive index of anoptically transmissive medium in contact with the transparent layer.

With this aspect of the invention, the liquid crystal layer in a regionin which a voltage equal to or more than the threshold voltage of theliquid crystal is applied by the at least one first electrode and the atleast one second electrode (hereinafter called “voltage applicationregion”) is set to a light-scattering state. Of this light, the lightthat is scattered forward with respect to the light-incident directionis incident on the transparent layer. This transparent layer has arefractive index that differs from that of the optically transmissivemedium in contact therewith. Thus, part of the forward-scattered lightpasses through the transparent layer, but, since there is adiscontinuity in refractive index at the interface between thetransparent layer and the optically transmissive medium, another partthereof is reflected by that interface. Therefore, bothbackward-scattered light and forward-scattered light generated in thevoltage application region of the liquid crystal layer strike the eyesof the observer, increasing the degree of light-scattering. This makesit possible to display a liquid crystal display pattern which is of acolor having a high level of brightness, such as white or gray, andwhich also has increased illuminance.

In a region in which no voltage is applied, or in which a voltage thatis less than the threshold voltage of the liquid crystal is applied,(hereinafter called “voltage non-application region”), the liquidcrystal layer is in a light-transmitting state so that light that isincident on the liquid crystal panel passes through the liquid crystallayer and the transparent layer, enabling a display of a backgroundpattern that is under the liquid crystal panel. Part of this throughlight is reflected by the interface between the transparent layer andthe optically transmissive medium. However, a result of making theliquid crystal display pattern brighter, by using forward-scatteredlight reflected from the interface between the transparent layer and theoptically transmissive medium, is to increase the contrast ratio betweenthat liquid crystal display pattern and the background pattern.

Thus, if sufficient light can be guaranteed to be reflected by thetransparent layer arid a background display portion such as the dialplate of a timepiece is provided on the rear side of the liquid crystalpanel, the display of the liquid crystal layer can be made conspicuous,even if the reflective surface of that background display portion has alow level of brightness.

In this case, it could be conceived to dispose a transparent layerbetween the liquid crystal panel and the background display portionduring the fabrication of a device that uses this liquid crystal panel,such as the above described two-layer display type of timepiece.Alternatively, it could be conceived to form a transparent layerbeforehand on the background display portion.

One of the checks performed on this type of liquid crystal panel beforethe final product is assembled is a visual check to ensure that theliquid crystal panel alone can display the desired image pattern whenused in practice. Since a transparent layer that makes the image patterneasy to see could be provided on the liquid crystal panel of thisinvention, the quality of the display can be determined reliably by avisual check of the liquid crystal panel alone. Therefore, if a displayfault should occur, it can of course be detected before the panel isassembled into electronic equipment.

In contrast thereto, if a transparent layer is first disposed in afinished product to which the panel is incorporated, as in theabove-described two conventional techniques, the image pattern isdisplayed by only backward-scattered light when the liquid crystal panelalone is checked, and it is therefore difficult to determine the qualityof the display.

Furthermore, since forward-scattered light can be reflected by thetransparent layer disposed within the panel in the liquid crystal panelof this invention, losses of the forward-scattered light can be reducedin comparison with structures in which the light is reflected outsidethe liquid crystal panel, as in the above-described two conventionaltechniques.

In addition, the occurrence of duplicated displays can be reduced if atwo-layer display type of electronic equipment is constructed by usingthe liquid crystal panel of this invention. In other words, since theliquid crystal layer that creates backward-scattered light and thetransparent layer that causes the reflection of forward-scattered lightare placed in contact by this invention, it is difficult for aduplicated display to occur, even when the line of sight is inclinedwith respect to the liquid crystal panel. Conversely, in theabove-described two conventional techniques, there is a large distancebetween the transparent layer that reflects the forward-scattered lightand the liquid crystal layer, so that duplicated displays can easilyoccur.

With this aspect of the invention, display quality can be improvedbecause the forward-scattered light is reflected back, but this effectis more striking if the quantity of light scattered forward in thelight-incident direction is greater than the quantity of light scatteredbackward against the light-incident direction.

In this case, a polymer dispersed liquid crystal layer comprising aliquid crystal and polymers can be exemplified as a liquid crystal layerthat can be set to a light-transmitting state or a light-scatteringstate, based on an applied voltage.

The at least one transparent layer can be formed of a material having arefractive index that differs from that of an optically transmissivemedium in contact therewith. Examples of such a transparent materialcould be glass, polymer films, transparent electrode materials, andinterference films. If an interference film is used, the display canalso be colored.

The at least one transparent layer could be formed to be in contact withthe second substrate. As an example thereof, a first main surface of theat least one transparent layer could be formed to be in contact with asurface on the opposite side of the second substrate from the opposingsurface. This configuration makes it possible to reduce the occurrenceof duplicated displays of the liquid crystal display pattern, becausethe transparent layer is in close contact with the liquid crystal layer.In this case, an optically transmissive medium in contact with thistransparent layer is the second substrate and the interfacetherebetween, which forms a reflective surface, is the first mainsurface. The transparent layer in this case may be formed of a materialhaving a different refractive index from the refractive index of thesecond substrate. More preferably, the at least one transparent layermay be formed of a material having a refractive index larger than therefractive index of the second substrate. This is more effective when,for example, a second main surface on the opposite side from the firstmain surface of the at least one transparent layer is formed to be incontact with an air layer. If this condition is set, and if therefractive index of the second substrate is n₀, the refractive index ofthe at least one transparent layer is n₁, and the refractive index ofthe air layer is n₂, the following relationship can be established:n₂<n₀<n₁. This configuration enables a large difference in refractiveindices between the second substrate and the transparent layer, thusincreasing the reflectance at the first main surface that is theinterface therebetween. In addition, the reflectance at a second mainsurface can be increased as a result of causing reflections at thissecond main surface, which is the interface between the transparentlayer and an air layer, and by creating a large difference in refractiveindices between the transparent layer and the air layer.

The at least one transparent layer may be formed of the same material asthe transparent electrode material that forms the at least one secondelectrode. By making the at least one second electrode formed on thesurface of the second substrate of the same material as the transparentlayer formed on the rear surface of the second substrate, the formationof films on the two surfaces of the second substrate can be done withthe same fabrication apparatus, increasing the throughput, which makesit possible to reduce the cost of the liquid crystal panel.

A material such as tin oxide may be used as the material utilized forboth the at least one transparent layer and the at least one secondelectrode. The refractive index of tin oxide (SnO₂) with respect tolight of a wavelength of 0.55 μm is 1.9. The second substrate isgenerally made of glass whose main component is SiO₂ (refractive indexapproximately 1.5), so if the refractive index of air is considered tobe 1.0, the above inequality becomes:

n₂=1.0<n₀=1.5<n₁=1.9

Thus n₁−n₀=0.4 and n₂−n₁=0.9, making it possible to ensure a largedifference in refractive indices.

The at least one transparent layer may be formed on a surface on theopposite side of the second substrate from the opposing surface, with anair layer therebetween. In this case, the optically transmissive mediumin contact with the transparent layer is the air layer, enabling thereflection of light from that interface. Therefore that transparentlayer is formed of a material having a refractive index that differsfrom the refractive index of the air layer.

The at least one transparent layer may be disposed between the liquidcrystal layer and the at least one second to electrode. In such a case,the optically transmissive medium in contact with the transparent layeris the at least one second electrode, enabling the reflection of lightfrom that interface. Therefore the transparent layer is formed of amaterial having a refractive index that differs from the refractiveindex of the at least one second electrode.

The at least one transparent layer may also be formed between the atleast one second electrode and the second substrate. In such a case, theoptically transmissive medium in contact with the transparent layer isthe at least one second electrode and the second substrate, enabling thereflection of light from both of those interfaces. Therefore thetransparent layer is formed of a material having a refractive index thatdiffers from the refractive indices of the at least one second electrodeand the second substrate.

The at least one transparent layer may be formed on part of a flatsurface region facing the liquid crystal layer. Such a configurationensures that forward-scattered light can be reflected by a region wherethe transparent layer exists, whereas this effect is not obtained in aregion with no transparent layer. Therefore, the viewer gets the feelingthat the former portion is a strongly contrasting display, whereas thelatter portion is a weakly contrasting display. This can be used tocreate different impressions depending on display position.

The at least one transparent layer may be formed of different materialshaving differing refractive indices, disposed in different locationswithin the same flat surface region facing the liquid crystal layer.Since the reflectance of the forward-scattered light varies withlocation in this configuration, this can be used to create differentimpressions in a manner similar to that described above.

A plurality of transparent layers may be formed in a stack. In such acase, if adjacent transparent layers are formed of materials havingdifferent refractive indices, the forward-scattered light can bereflected at each of the interfaces between the transparent layers.

More specifically, the liquid crystal panel may be configured in such amanner that first to Nth (where N≧2) of these the transparent layers arestacked on one another, and adjacent transparent layers are formed ofmaterials having different refractive indices;

the first transparent layer located in a previous stage in thelight-incident direction is formed to be in contact with a surface onthe opposite side of the second substrate from the opposing surface, andthe Nth transparent layer is formed to be in contact with an air layer;and

the refractive indices of the first to Nth transparent layers are set toincrease in the light-incident direction.

With this configuration, forward-scattered light can be reflected ateach of the interfaces between the transparent layers and, in addition,a large difference in refractive indices can be ensured between the Nthtransparent layer and the air layer, so that the reflectance at thatinterface can be made large.

In this structure in which a plurality of transparent layers arestacked, it is also possible to vary the number of superimposedtransparent layers at different locations within the region facing theliquid crystal layer. In this case too, the reflectance of theforward-scattered light can be varied in different locations, which canvary the impressions imparted by the display; in a similar manner tothat described above.

According to another aspect of this invention, there is providedelectronic equipment, comprising:

a liquid crystal panel which is disposed on a side on which externallight is incident; and

a background display portion which is disposed forward of the liquidcrystal panel with respect to the light-incident direction;

wherein the liquid crystal panel comprises:

a first substrate which is disposed on the side on which external lightis incident and on which at least one first electrode is formed;

a second substrate which is disposed facing the first substrate and onwhich at least one second electrode is formed;

a liquid crystal layer which is inserted between opposing surfaces ofthe first and second substrates and which is set to one of alight-transmitting state and a light-scattering state, based on avoltage applied between the at least one first electrode and the atleast one second electrode, to make the background display portionvisible when in the light-transmitting state; and

at least one transparent layer disposed forward of the liquid crystallayer in the light-incident direction,

wherein the at least one transparent layer is formed of a materialhaving a refractive index that differs from the refractive index of anoptically transmissive medium in contact with the transparent layer.

This electronic equipment is configured of the liquid crystal panel inaccordance with this invention and a background display portion providedon the rear side thereof. With this electronic equipment, a stronglyilluminated liquid crystal display pattern can be displayed in a regionwhere the liquid crystal layer of the above liquid crystal panel hasbeen set to the light-scattering state and, in addition, it is possibleto see the background display portion in a region where the liquidcrystal layer has been set to the light-transmitting state. In otherwords, a number of different displays can be seen at the same time.

Since the forward-scattered light is reflected at the interface with thetransparent layer even when the background display portion comprises alight-reflecting portion of a low brightness, the illuminance of theliquid crystal display pattern does not fall.

This background display portion may be an analog timepiece comprising adial plate and an indicator means, for example, in which case thisinvention has the effect of reducing restrictions on the dial platedesign.

If the background display portion is of a color having a low brightness,the background display portion could be difficult to see at times,mainly at night-time, so an illumination means may be provided toilluminate this background display portion.

This background display portion is not limited to a means of forming adisplay from the light passing through a liquid crystal panel; it mayinclude a light-emitting portion that emits an optical pattern of abackground image. Such a background display portion could be configuredof a backlit liquid crystal panel for a background image display, ormeans for self-generating light from an electrical supply, such as anLED. In such a case, the background display portion can be seen in abright state, even when only a small amount of external light is passingthrough the liquid crystal panel, such as at night.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic side view of essential components of a two-layerdisplay type of timepiece provided with a liquid crystal panel inaccordance with a first embodiment of this invention;

FIG. 2 is a front view of the essential components of the firstembodiment;

FIG. 3 is a cross-sectional view through the liquid crystal panel of thefirst embodiment of this invention;

FIG. 4 is a graph of the relationship between the optical film thicknessand reflectance of the transparent layers used in the liquid crystalpanel of the first embodiment;

FIG. 5 is a cross-sectional view through a liquid crystal panel of asecond embodiment of this invention;

FIG. 6 is a cross-sectional view through a liquid crystal panel of athird embodiment of this invention;

FIG. 7 is a front view of essential components relating to an example ofthis third embodiment;

FIG. 8 is a front view of essential components relating to anotherexample of this third embodiment;

FIG. 9 is a cross-sectional view through a liquid crystal panel of afourth embodiment of this invention;

FIG. 10 is a cross-sectional view through a liquid crystal panel of afifth embodiment of this invention;

FIG. 11 is a cross-sectional view through a liquid crystal panel of asixth embodiment of this invention;

FIG. 12 is a cross-sectional view through a liquid crystal panel of aseventh embodiment of this invention;

FIG. 13 is a cross-sectional view through a liquid crystal panel of aneighth embodiment of this invention;

FIG. 14 is a cross-sectional view through a two-layer display type oftimepiece relating to a ninth embodiment of this invention; and

FIG. 15 is an exploded perspective view of the two-layer display type oftimepiece of FIG. 14.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be described below withreference to the accompanying drawings.

First Embodiment

First of all, FIG. 1 is a schematic side view of essential components ofa two-layer display type of timepiece (electronic equipment) which isprovided with a liquid crystal panel in accordance with a firstembodiment of this invention. As shown in the figure, this two-layerdisplay type of timepiece receives light which is incident from adirection A, and has a liquid crystal panel 1 that provides afirst-layer display. There is also a background display portion 2 thatprovides a second-layer display, disposed forward of the liquid crystalpanel 1 in this direction A.

The liquid crystal panel 1 comprises a main liquid crystal panel unit10, a ultraviolet-blocking film 20 that covers substantially the entirefront surface of the main liquid crystal panel unit 10, and atransparent layer 21 that covers substantially the entire rear surfaceof the main liquid crystal panel unit 10. The main liquid crystal panelunit 10 will be described later.

The background display portion 2 that is disposed on the rear side ofthe liquid crystal panel 1 is configured as an analog timepiece. Inother words, the background display portion has a dial plate 22, and acasing 23 for the movement of a timepiece is disposed on the rear sidethereof. An hour hand 24, a minute hand 25, and a second hand 26 aredisposed on the surface of the dial plate 22, and these hands 24, 25,and 26 are driven by the movement within the casing 23. Note that themain liquid crystal panel unit 10, the dial plate 22, and the casing 23are held by means such as a frame member (not shown in the figure) insuch a manner that they are mutually parallel.

As shown in FIG. 2, this two-layer display type of timepiece provides adigital information display by the main liquid crystal panel unit 10 andan analog time display by the background display portion 2. In FIG. 2, aday-of-the-week display “mo” and a date display “12-24” are digitaldisplays provided by the main liquid crystal panel unit 10. Tick marks27 are formed on the dial plate 22 to enable the analog time display bythe hands 24, 25, and 26. Note that the information display provided bythe main liquid crystal panel unit 10 is not limited to displays of theday of the week and the date, and various other displays are possiblesuch as times, a timer, a stopwatch, or an alarm.

An expanded cross-sectional view of the liquid crystal panel 1 is shownin FIG. 3. The main liquid crystal panel unit 10 is provided with afirst substrate 11, a plurality of segment electrodes (first electrodes)12, a liquid crystal layer 13, a plurality of common electrodes (secondelectrodes) 14, and a second substrate 15. The first and secondsubstrates 11 and 15 are formed of a transparent material; they could beformed from glass of a refractive index 1.5, by way of example. Theplurality of segment electrodes 12 and the common electrodes 14 are alsoformed of transparent material, with the plurality of common electrodes14 extending along the second substrate 15 in a single direction and theplurality of segment electrodes 12 extending along the first substrate11 in another direction perpendicular to that single direction. Itshould be noted, however, that a single common electrode could be formedover substantially the entire surface of the second substrate. The firstsubstrate 11 and second substrate 15 are disposed parallel to oneanother in such a manner that the plurality of segment electrodes 12 andthe common electrodes 14 face each other, and the liquid crystal layer13 is injected between these two substrates. The spacing of the firstand second substrates 11 and 15 is preferably 3 to 20 μm.

Note that a seal member 28 forms a seal between the outer edges of thefirst substrate 11 and the second substrate 15, to prevent the liquidcrystal layer 13 from leaking. The mutually opposing surfaces of thefirst substrate 11 and the second substrate 15 are subjected toorientation processing. In addition, the surface of the first substrate11, in other words, the surface on the outer side facing the viewer, ispreferably subjected to anti-reflective processing or non-glareprocessing, to greatly improve the visibility.

The liquid crystal layer 13 used by the main liquid crystal panel unit10 is of a polymer dispersion type, which has the characteristic ofturning transparent in regions in which no voltage is applied, butcauses light to diffuse or scatter in regions in which a voltage isapplied. In other words, if a voltage that is equal to or more than thethreshold voltage of the liquid crystal is applied between the segmentelectrodes 12 and the common electrodes 14, white or gray is seen by theuser and thus the day-of-the-week display “mo” and the date display“12-24” are made visible.

The method of fabricating the liquid crystal layer 13 is describedbelow. First of all, a mixed liquid in which polymers or polymerprecursors and the crystal are dissolved is injected between the firstand second substrates 11 and 15. The liquid crystal and the polymers arethen separated. This orientates the liquid crystal and the polymers withrespect to each other within the liquid crystal layer 13. Note that thisoriented state could be one in which particles or combined particles ofpolymers are distributed within the liquid crystal, or one in which thepolymers are in a mesh-like gel state within the liquid crystal. Itcould also be an oriented state in which droplets of the liquid crystalare distributed within the polymers.

Vinyl compounds such as acrylate; compounds that can be polymerized bylight or electron beams, such as epoxy compounds; or compounds that canbe polymerized by heat, such as epoxy compounds; could be used as theabove polymer precursors, in addition to methacrylates such as biphenylmethacrylate. Compounds that are polymerized by light or electron beamsare illuminated with light of a suitable wavelength or an electron beam,to separate them from the liquid crystal. Compounds that are polymerizedby heat are heated to an appropriate temperature to separate them fromthe liquid crystal.

Thermoplastic polymers such as ethyl cellulose could be used. In such acase, if the polymers and the liquid crystal are dissolved in a heatedstate, separation will occur on cooling.

Note that a chiral component could be included within the liquid crystalcomponents. This would scatter light effectively, thus making thedisplay within the liquid crystal more easily visible. Any ordinarychiral component could be used as the chiral component in thisembodiment, provided it can exert a twisting power on the orientation ofthe liquid crystal.

As an example, 90% by weight of a main liquid crystal component (productname: BL007, made by Merck KGaA), 3% by weight of a chiral component(product name: CB15, made by Merck KGaA), and 7% by weight of a polymerprecursor (biphenyl methacrylate) were mixed together and injectedbetween the substrates 11 and 15. Ultraviolet light was then shone ontothis mixed liquid, so that phase separation occurred with the liquidcrystal and the polymers mutually orientated. This formed the liquidcrystal layer 13. The thus fabricated liquid crystal panel had a drivevoltage of approximately 5 V, so that this panel can sufficiently bedriven by an IC for a prior-art timepiece.

Note that if liquid crystal having a positive anisotropy of dielectricconstant is used, the opposing surfaces of the first and secondsubstrates 11 and 15 are preferably processed to have a homogeneousalignment. If liquid crystal having a negative anisotropy of dielectricconstant is used, the opposing surfaces of the first and secondsubstrates 11 and 15 are preferably processed to have a homeotropicalignment.

The liquid crystal layer 13 in the resultant main liquid crystal panelunit 10 has the property of being transparent when no electrical fieldis applied, but light is diffused thereby when an electrical field isapplied. Therefore, if an electrical field is applied between thesegment electrodes 12 and the common electrodes 14, the portiontherebetween appears to the user to be colored, which makes the abovedescribed display visible, as shown in FIG. 2. Portions where theelectrical field is not applied are transparent, so that the analogdisplay expressed by the dial plate 22 and the hands 24, 25, and 26 canbe seen therethrough.

The color of this colored display is white or gray (although it shouldbe noted that this invention is not to be taken as being limited towhite). To emphasize the liquid crystal panel that appears as white orgray, the dial plate 22 is preferably of a color that has a lowbrightness, such as black, dark blue, or dark red.

Alternatively, the dial plate 22 is preferably reflective. In such acase, the reflected light amplifies the scattering within the liquidcrystal display portions, which applies contrast between the display ofthe liquid crystal and the other portions, and thus makes the displaymore obvious. It is particularly suitable to apply a mirror surface tothe dial plate 22.

As shown in FIG. 3, a single transparent layer 21 is formed in directcontact with the rear surface of the second substrate 15 of the mainliquid crystal panel unit 10.

The basic concept of the display provided by the liquid crystal panel 1having this transparent layer 21 will now be described. The descriptionfirst concerns a case in which an electrical field is applied to theliquid crystal layer 13 between the segment electrodes 12 and the commonelectrodes 14.

In this case, light that is incident from the direction of the arrow Ais scattered within the region of the liquid crystal layer 13 to whichthe voltage is applied. This scattered light comprises forward-scatteredlight B that continues forward in the light-incident direction A andbackward-scattered light C that is scattered backward with respect tothe light-incident direction A, as shown in FIG. 3. With this liquidcrystal layer 13 in particular, research by the present inventors hasdetermined that the quantity of forward-scattered light B tends to begreater than that of the backward-scattered light C.

The backward-scattered light C strikes the eyes of the observerdirectly, through the first substrate 11 and the ultraviolet-blockingfilm 20, but the forward-scattered light B does not reach the eyes ofthe observer, unless it is reflected back.

The transparent layer 21 is provided to ensure that this embodimentcauses the large quantity of forward-scattered light B to be reflected.More specifically, part of the forward-scattered light B passes throughthe transparent layer 21, but the remainder is reflected at the boundarysurface between the second substrate 15 and the transparent layer 21 sothat it returns towards the front. Part of the forward-scattered light Bthat has passed through the transparent layer 21 proceeds onwardstowards the outer air, but the remainder is reflected at the boundarysurface between the transparent layer 21 and the air so that it returnstowards the front. The degree of scattering of the light from the liquidcrystal layer 13 that strikes the eyes of the observer is increased bythe thus-reflected forward-scattered light B, making the display shownon the liquid crystal panel even brighter and thus making it clearlyvisible.

If the light reflected from the transparent layer 21 is sufficient,therefore, the display of the liquid crystal layer 13 can be made moreconspicuous and thus clearly visible, even if the dial plate 22 is of alow brightness.

In a configuration in which there is a single transparent layer 21, therefractive index of the transparent layer 21 is preferably made largerthan the refractive index of the second substrate 15. In other words, itis preferable that the relationship expressed by Equation 1-1 issatisfied, and more preferable that the relationship of Equation 1-2 issatisfied.

n₀<n₁  (Equation 1-1)

n₂<n₀<n₁  (Equation 1-2)

where: n₀ is the refractive index of the second substrate 15, n₁ is therefractive index of the transparent layer 21, and n₂ is the refractiveindex of air (value=1).

Ordinarily, more of the light incident from the front is reflected bythe boundary surface between the second substrate 15 and the transparentlayer 21 as the difference between the refractive index n₀ of the secondsubstrate 15 and the refractive index n₁ of the transparent layer 21 onthe rear side thereof increases, making it possible for the displayshown by the light-scattering type of liquid crystal panel to be clearerand brighter. Similarly, more of the light incident from the front isreflected by the boundary surface between the transparent layer 21 andthe air layer behind it as the difference between the refractive indexn₁ of the transparent layer 21 and the refractive index n₂ of the air onthe rear side thereof increases, making it possible for the displayshown by the light-scattering type of liquid crystal layer 13 to beclearer and brighter. Furthermore, very little of the light incidentfrom the air at the rear is reflected by the boundary surface betweenthe transparent layer 21, which has a large refractive index, and thesecond substrate 15, which has a small refractive index, so this alsomakes it possible for the display shown by the light-scattering type ofliquid crystal layer 13 to be clearer and brighter.

Conversely, if the refractive index of the transparent layer 21 is madeto be smaller than the refractive index of the second substrate 15, thedifference between the refractive indices of the transparent layer 21and the air layer on the rear side thereof is reduced, so that theeffect of light incident from the front being reflected by the boundarysurface between the transparent layer 21 and the air layer is reduced.In addition, more of the light incident from the air layer at the rearis reflected by the boundary surface between the transparent layer 21,which has a small refractive index, and the second substrate 15, whichhas a large refractive index.

It should be noted, however, that the reflectance is not alwaysincreased, depending on the relationship between the light wavelength Aand the optical film thickness n₁·d₁ of the transparent layer 21, evenif the refractive index of the transparent layer 21 is large. This pointwill now be discussed with reference to FIG. 4 and Equations 2 and 3.

n₁·d₁=(2m+1) λ/4  (Equation 2)

n₁·d₁=(m+1) λ/2  (Equation 3)

As can be seen from FIG. 4, reflectance increases when the relationshipis as stated by Equation 2, or is close thereto, but the increasing rateof the reflectance is reduced when the relationship is as stated byEquation 3, or is close thereto. In this case, n₁ is the refractiveindex of the transparent layer 21, d₁ is the thickness of thetransparent layer 21, λ is the wavelength of light, and m is an integergreater than or equal to zero (0,1,2, . . . ).

Examples given below are those of combinations of the second substrate15 and the transparent layer 21 that satisfy the above relationship thatthe refractive index of the transparent layer 21 should be greater thanthe refractive index of the second substrate 15.

(1) If the second substrate 15 is formed of ordinary glass (refractiveindex 1.5), of which the main component is SiO₂, suitable materials forthe transparent layer 21 would include: NdF₃ (refractive index 1.61),CeF₃ (refractive index 1.63), PbF₂ (refractive index 1.75), ZnS(refractive index 2.3), CdS (refractive index 2.5 (0.6 μm)), ZnSe(refractive index 2.57 (0.6 μm)), ZnTe (refractive index 2.8), Sb₂S₃(refractive index 3.0), PbTe (refractive index 5.6 (5.0 μm)), Si(refractive index 3.4 (3.0 μm)), Ge (refractive index 4.4 (2.0 μm)),Sno₂ (refractive index 1.9), SiO (refractive index 2.0 (0.7 μm)), Al₂O₃(refractive index 1.6), MgO (refractive index 1.7), ThO₂ (refractiveindex 1.86), La₂O₃ (refractive index 1.9), CeO₂ (refractive index 2.2),ZrO₂ (refractive index 2), Ta₂O₅ (refractive index 2.1), TiO₂(refractive index 1.9), PbO (refractive index 2.6), and ITO (refractiveindex 1.8). Note that the values in parentheses after each refractiveindex give the wavelength at which that refractive index was measured,and this wavelength is 0.55 μm if no value is given in parentheses.

(2) If the second substrate 15 is formed of sapphire glass (Al₂O₃(refractive index 1.6)), suitable materials for the transparent layer 21would be any of the above list of materials that have refractive indicesgreater than 1.6.

By utilizing the relationships described in relation to the aboveEquations 2 and 3, light of a special wavelength could be reflectedtoward mainly the front side, or light over all wavelengths could bereflected toward the front side.

The common electrodes 14 formed on the front surface of the secondsubstrate 15 could be made of the same material as that of thetransparent layer 21 formed on the rear surface of the second substrate15. If this is so, the formation of films on the front and rear surfaceof the second substrate 15 could be done by the same film-formationapparatus, improving the throughput. Since it is necessary to form thesecond electrodes of a transparent electrode material in such a case,the transparent layer 21 can also be formed of that transparentelectrode material. This transparent material could be tin oxide (SnO₂)or indium tin oxide (ITO), or the like. Of these materials, tin oxide isparticularly useful because tin oxide has a greater refractive indexthan other transparent electrode materials and thus it can ensure agreater difference in refractive indices between the second substrate 15and the air layer.

Note that the transparent layer 21 is not limited to being disposed incontact with the second substrate 15; an air layer could equally well beformed between the second substrate 15 and the transparent layer 21. Insuch a case, the optically transmissive medium in contact with thetransparent layer 21 is an air layer, and light van be reflected fromthat interface. The transparent layer 21 should therefore be made of amaterial having a refractive index that differs from the refractiveindex of that air layer.

Second Embodiment

In a second embodiment of the liquid crystal panel 1 of this invention,shown in FIG. 5, further transparent layers 21 a, 21 b, and 21 c areprovided below the transparent layer 21, and all of the transparentlayers 21, 21 a, 21 b, and 21 c are in direct contact. In this case, therefractive index of each transparent layer preferably differs from therefractive indices of the other transparent layers and the secondsubstrate 15.

It is difficult to represent this configuration by a simple logicalrelationship such as Equation 1, but it is possible to cause repeatedreflections at the boundary surfaces between the transparent layers,depending on the combination of refractive indices of the transparentlayers, thus illuminating the display in the liquid crystal layer 13more brightly.

Third Embodiment

A third embodiment of the liquid crystal panel 1 in accordance with thisinvention is shown in FIG. 6. Although the transparent layer 21 isprovided over substantially the entire rear surface of the secondsubstrate 15 in the liquid crystal panel 1 of the first embodiment, inthis embodiment the transparent layer 21 is attached in correspondencewith a part of the rear surface of the second substrate 15.

This configuration provides the effect of illuminating brightly only apart of the liquid crystal layer 13 corresponding to the region in whichthe transparent layer 21 and the second substrate 15 are superimposed.In contrast, this effect is not achieved in a portion of the liquidcrystal layer 13 corresponding to a region in which the transparentlayer 21 is not formed. Therefore, the viewer gets the feeling that theformer portion is a strongly contrasting display, whereas the latterportion is a weakly contrasting display. This can be used to createdifferent impressions depending on display position.

A front view of essential components of a timepiece that uses the liquidcrystal panel 1 of FIG. 6 is shown in FIG. 7. An edge border 29 of thetransparent layer 21 of FIG. 6 is located around the day-of-the-weekdisplay shown in FIG. 7. More specifically, the day-of-the-week displayportion that shows “mo” is a portion that does not correspond to thetransparent layer 21 but the date display portion that shows “12-24” isa portion that does correspond to the transparent layer 21. Thus thedate display can be made clearly visible in comparison with theday-of-the-week display. This kind of display can be used in many otherways.

Another example of the use of the liquid crystal panel 1 of FIG. 6 isshown in FIG. 8. The display in FIG. 8 is opposite to that of FIG. 7 inthat the day-of-the-week display portion that shows “mo” is a portionthat does correspond to the transparent layer 21 but the date displayportion that shows “12-24” is a portion that does not correspond to thetransparent layer 21. Thus the day-of-the-week display can be madeclearly visible in comparison with the date display.

Fourth Embodiment

A fourth embodiment of the liquid crystal panel 1 in accordance withthis invention is shown in FIG. 9. In the liquid crystal panel 1 of thisfourth embodiment, the transparent layer 21 is attached incorrespondence with a part of the rear surface of the second substrate15, whereas another transparent layer 31 is attached in correspondencewith another part thereof. The refractive indices of the transparentlayers 21 and 31 are different from each other. In other words,transparent layers 21 and 31 formed of materials having differentrefractive indices are disposed on the same flat surface in thisembodiment.

With this embodiment, the impression of the display portion of theliquid crystal layer 13 corresponding to the transparent layer with thelarger refractive index can be made different from the impression of thedisplay portion of the liquid crystal layer 13 corresponding to thetransparent layer with the smaller refractive index. This enablesvarious different displays, such as those shown in FIG. 7 or FIG. 8.

Fifth Embodiment

A fifth embodiment of the liquid crystal panel 1 in accordance with thisinvention is shown in FIG. 10. In the liquid crystal panel 1 of thisfifth embodiment, a plurality of the transparent layers 21, 21 a, and 21b are provided in a stack, in the same manner as in the secondembodiment of FIG. 5. In addition, the transparent layer 21 acorresponds to only a part of the other transparent layers 21 and 21 band is attached thereto. Reference number 29 in this figure denotes anedge border of the transparent layer 21 a, and is equivalent to the edgeborder 29 of FIGS. 7 and 8.

With this embodiment, the display portion of the liquid crystal layer 13corresponding to the three transparent layers 21, 21 a, and 21 b can bemade to give a different impression from that of the display portion ofthe liquid crystal layer 13 corresponding to the two transparent layers21 and 21 b alone. This enables various different displays, such asthose shown in FIG. 7 or FIG. 8. Note that the number of transparentlayers is not limited to that shown in the figure, and any of thetransparent layers can be formed to be smaller, as shown by thetransparent layer 21 a in the figure.

It should also be noted that transparent layers formed of materialshaving different refractive indices could be disposed on the same flatsurface, if a plurality of such transparent layers are provided, in thesame manner as the third embodiment shown in FIG. 9.

Sixth Embodiment

A sixth embodiment of the liquid crystal panel 1 in accordance with thisinvention is shown in FIG. 11. In the liquid crystal panel 1 of thissixth embodiment, a transparent layer 41 is disposed between the polymerdispersion type of light-scattering liquid crystal layer 13 and thesecond substrate 15. In this case, a plurality of common electrodes 14are formed at a suitable spacing on the second substrate 15. Thus thetransparent layer 41 is formed to cover the plurality of commonelectrodes 14 in the portions in which the common electrodes 14 areprovided. The transparent layer 41 is formed over the second substrate15 in portions in which there are no common electrodes 14. Thistransparent layer 41 is formed of an insulating material, to preventshorting between adjacent common electrodes 14.

During the fabrication of this liquid crystal panel 1, the transparentlayer 41 is previously formed over the surfaces of the second substrate15 and the common electrodes 14, then the first substrate 11 and thesecond substrate 15 are linked together.

Assume in this case that the material of the transparent layer 41 ofthis sixth embodiment is Al₂O₃ (refractive index 1.6), the material ofthe common electrodes 14 is SnO₂ (refractive index 1.9), and thematerial of the second substrate 15 is SiO₂ (refractive indexapproximately 1.5).

With the above configuration, light that is incident from the front sideand has passed through the transparent layer 41 is reflected asdescribed below. In other words, part of this through light is reflectedby each of the boundary surface between the transparent layer 41 and theplurality of common electrodes 14, the boundary surface between theplurality of common electrodes 14 and the second substrate 15, and theboundary surface between the transparent layer 41 and the secondsubstrate 15, and returns towards the front side. Part of the light thathas passed through the second substrate 15 proceeds onwards towards theair, but the remainder is reflected by the boundary surface between thesecond substrate 15 and the air and returns towards the front side.

In this case, the area occupied by the plurality of common electrodes 14formed on the second substrate 15 is greater than total surface areaover which no common electrodes 14 are formed, from considerations ofensuring a sufficiently high aspect ratio. Therefore, with this sixthembodiment, the total surface area of the boundary surface between theplurality of common electrodes 14 and the second substrate 15 is greaterthan the total surface area of the boundary surface between thetransparent layer 41 and the second substrate 15.

Since there is thus a large difference in refractive indices(1.9−1.5=0.4) at the wide boundary surface between the common electrodes14 and the second substrate 15, reflectance at that boundary surface isincreased. Note that the total surface area of the boundary surfacebetween the transparent layer 41 and the plurality of common electrodes14 can also be guaranteed to be large, so that large amounts ofreflection can be expected here too. It is therefore better to chosematerials with a large difference in refractive indices at the boundarysurface between the transparent layer 41 and the plurality of commonelectrodes 14.

The light that has been reflected in this manner ensures that thedisplay shown by the light-scattering liquid crystal layer 13 can bemade bright and is thus clearly visible.

Note that the common electrodes 14 could be provided on the rear surfaceof the first substrate 11 with the segment electrodes 12 being providedon the front surface of the second substrate 15, as a variation on theabove configuration. In such a case too, it is preferable that thetransparent layer 41 is formed of an insulating material. If thetransparent layer 41 were formed of a conductive material in such acase, an electrical field would be generated between the commonelectrodes 14 and the transparent layer 41 in contact with the segmentelectrodes 12, making it impossible to show any display at locationscorresponding to the segment electrodes 12.

Seventh Embodiment

A seventh embodiment of the liquid crystal panel 1 in accordance withthis invention is shown in FIG. 12. In the liquid crystal panel 1 ofthis seventh embodiment, an insulating transparent layer 41 is formed onthe front side of the second substrate 15 and the common electrodes 14are then formed thereupon. Other details are the same as those of thesixth embodiment of FIG. 11.

Assume in this case that the material of the transparent layer 41 ofthis seventh embodiment is TiO₂ (refractive index 1.9), the material ofthe common electrodes 14 is ITO (refractive index 1.8), and the materialof the second substrate 15 is SiO₂ (refractive index approximately 1.5).

With the above configuration, light that is incident from the front sideand has passed through the transparent layer 41 is reflected asdescribed below. In other words, part of this through light is reflectedby each of the boundary surface between the transparent layer 41 and theplurality of common electrodes 14 and the boundary surface between thetransparent layer 41 and the second substrate 15, and returns towardsthe front side. Part of the light that has passed through the secondsubstrate 15 proceeds onwards towards the air, but the remainder isreflected by the boundary surface between the second substrate 15 andthe air and returns towards the front side.

The widest reflective surface that can be ensured in this seventhembodiment is the boundary surface between the transparent layer 41 andthe second substrate 15, and this embodiment ensures that there is alarge difference in refractive indices (1.9−1.5=0.4) at that boundarysurface.

The light that has been reflected in this manner makes it possible forthe display shown by the light-scattering liquid crystal layer 13 to bebright and is thus clearly visible.

Note that the common electrodes 14 could be provided on the rear surfaceof the first substrate 11 with the segment electrodes 12 being providedon the front surface of the second substrate 15, as a variation on theabove configuration. In this case too, the transparent layer 41 ispreferably formed of an insulating material.

In the above sixth and seventh embodiments, the refractive index of thesecond substrate is preferably made to be larger than the refractiveindices of the transparent layer 41 and air, to increase the reflectanceat the boundary surface between the second substrate 15 and the air. Tosatisfy the relationship of Equation 1-1, therefore, reference numbersno and n₁ could be defined as shown below, in other words, n₀ inEquation 1-1 is the refractive index of the transparent layer 41 and n₁is the refractive index of the second substrate 15. If n₁ is therefractive index of the second substrate 15 and d₁ if the thickness ofthe second substrate 15, the relationships described with reference toFIG. 4 and Equations 2 and 3 can be satisfied.

With such a configuration, the scattering at the liquid crystal layer 13that reaches the eyes of the observer is further increased. This makesit possible for the display provided by the light-scattering liquidcrystal layer 13 to be even more clearly visible.

If the second substrate 15 is made of a glass which always has SiO₂ as amain component (refractive index 1.5), there are few materials for thetransparent layer 41 that satisfy these conditions, but if the secondsubstrate 15 is made of Al₂O₃ (refractive index 1.6), SiO₂ can be usedfor the transparent layer 41.

Eighth Embodiment

An eighth embodiment of the liquid crystal panel 1 in accordance withthis invention is shown in FIG. 13. In the liquid crystal panel 1 ofthis eighth embodiment, a transparent layer 41 a having a differentrefractive index is superimposed on the front side of the transparentlayer 41.

It is difficult to represent this configuration by a simple logicalrelationship such as Equation 1-1, but reflections can be repeated ateach of the boundary surfaces between the transparent layers 41 and 41a, the common electrodes 14, and the second substrate 15, depending onthe combinations of refractive indices of the transparent: layers, thusenabling a clearer and brighter display from the light-scattering liquidcrystal layer 13. There can be any number of transparent layers,provided the electrical field that is generated between segmentelectrodes 12 and the common electrodes 14 is not impeded thereby.

Note that it is possible to impart different impressions depending ondisplay position with the sixth or eighth embodiment too, by providing apartial transparent layer in a manner similar to that of the thirdembodiment of FIG. 6, by providing transparent layers of differingrefractive indices on the same flat surface in a manner similar to thatof the fourth embodiment of FIG. 9, or by providing partial transparentlayers in a manner similar to that of the fifth embodiment of FIG. 10.

Ninth Embodiment

A specific example of the use of the liquid crystal panel 1 of the firstto eighth embodiments, in a two-layer display type of timepiece will nowbe described with reference to FIGS. 14 and 15.

This liquid crystal panel 1 is held by an annular outer panel frame 51and an annular panel restraining member 52 that fits into the outerpanel frame 51, and the liquid crystal panel 1, the outer panel frame51, and the panel restraining member 52 together form a panel unit 50.

A watch stem 53 is attached to the casing 23 of the analog movement,extending in a sideways direction. The casing 23 is mounted into acircuit case 47 made of resin. A circuit board 48 is attached to a rearside of the circuit case 47 and a metal circuit pressing plate 49 isattached to the rear side thereof.

Four hooks 54 are formed around an edge portion of the circuit pressingplate 49, as shown in FIG. 15, and these hooks 54 are bent upward.Engagement pieces 55 are provided protruding outward from four locationson the outer periphery of the outer panel frame 51, to correspond to thefour hooks 54. The panel unit 50 is mounted on the circuit pressingplate 49 with the circuit case 47 and the circuit board 48 sandwichedtherebetween, by engaging the hooks 54 into the corresponding engagementpieces 55.

Note that grooves 59 are provided at four locations at 90 degrees aroundthe outer peripheral surface of the outer panel frame 51, as shown inFIG. 15. The four grooves 59 are formed along the axial direction of theouter panel frame 51 and the engagement pieces 55 protrude into thecenters of these grooves 59.

A storage compartment for a battery (not shown in the figure) isprovided in the circuit case 47. One terminal of this battery isconnected to the circuit pressing plate 49 and the other terminalthereof is connected to a terminal of circuitry provided on the circuitboard 48. The analog movement is supplied with power by the circuitboard 48 supported by the circuit pressing plate 49.

A circuit for supplying power to the liquid crystal panel 1 is alsoformed on the circuit board 48. Reference number 56 denotes zebraconnectors that are connected to the liquid crystal panel 1 and thecircuitry on the circuit board 48. Three of these zebra connectors 56are provided, as shown in FIG. 15. These zebra connectors 56 areretained by retaining apertures 57 of the circuit case 47, as shown inFIG. 14, passing through corresponding through holes 58 formed betweenthe outer panel frame 51 and the panel restraining member 52. Each ofthe zebra connectors 56 has a thin-plate form and includes an insulatingand elastic main body, in which are provided condustors as a pluralityof conductive paths at predetermined locations. Circuit terminals on thecircuit board 48 are connected to terminals of the liquid crystal panel1 by these conductive paths.

The internal structure of this timepiece is covered by an upper case 3,a lower case 4, a rear cover 5, and a protective glass 6 on the frontside that also provide external protection, so that only the operationalportion of the watch stem 53 is exposed.

Note that the first substrate 11 and the second substrate 15 of theliquid crystal panel 1 are formed to have an octagonal shape and aresuperimposed as shown in FIG. 15. The first substrate 11 is formed to beslightly bigger than the second substrate 15 so that, when the twosubstrates are superimposed, parts of the substrate 11 in front protrudefurther outward than the second substrate 15. Three such extendedportions 11 a are provided, the terminals of the liquid crystal panel 1are formed or the rear sides of these extended portions 11 a, and theseterminals are connected to the conductive paths formed in the zebraconnectors 56.

The profile of the inner side of the panel restraining member 52 is of acircular ring shape as shown in FIG. 15 and this member is formed ofresin. The profile 52 b of the outer side of the panel restrainingmember 52 is formed to resemble an octagonal shape such that it fits theouter panel frame 51.

During the assembly of this two-layer display type of timepiece, theliquid crystal panel 1 is incorporated into the panel unit 50. At thispoint, the liquid crystal panel 1 has a configuration such that theultraviolet-blocking film 20 is attached to the surface of the mainliquid crystal panel unit 10 and the transparent layer 21 is attached tothe rear surface thereof, and the ultraviolet-blocking film 20 or thetransparent layer 21 are extremely prone to damage, depending on thematerials thereof. However, such defects can be prevented by handlingthe assembly as the panel unit 50.

Once the liquid crystal panel 1 is sandwiched between the outer panelframe 51 and the panel restraining member 52, however, the panel 1 isheld away from the surface of the worktable, for example, even if thepanel unit 50 is placed directly thereon. This makes it possible toreduce the danger of damage to the panel 1.

Further Variations

To make the white or gray information display on the liquid crystallayer 13 more conspicuous, a transparent layer having a high refractiveindex could be provided on the dial plate 22 by means such as vapordeposition, in addition to forming a mirror surface for the dial plate22. In this case, a plurality of such transparent layers could besuperimposed. The dial plate 22 could also be of a color of a low levelof brightness, such as black.

A two-layer display type of electronic equipment in accordance with thisinvention is not limited to a timepiece provided with an analog displaymeans that provides a display by the dial plate 22 and the hands 24, 25,and 26. For example, the background display portion provided behind theliquid crystal panel 1 could be such that the background can be seenthrough regions where the liquid crystal layer of the liquid crystalpanel 1 are in a transmissive state. This background display portioncould also be a board on which is formed a pattern drawn of letters andpictures. Alternatively, the background display portion could be anotherliquid crystal panel showing a second-layer liquid crystal display,which is provided on the rear surface side of the liquid crystal panel 1which shows a first-layer liquid crystal display. The liquid crystalpanel for the second-layer liquid crystal display could be atransmissive type provided with a backlight or a reflective type. If thebackground display portion is a backlit liquid crystal panel, the lightfrom the backlighting can be guided towards the first-layer liquidcrystal panel 1 on the front side thereof. Alternatively, anillumination light source could be provided between the liquid crystalpanel 1 and the background display portion on the rear side thereof, sothat light is generated from behind the liquid crystal panel 1. Lightfrom the rear of the first-layer liquid crystal panel 1 would make thedisplay of the liquid crystal panel 1 more clearly visible, withouthindering it. In addition, if light is generated from behind this firstliquid crystal panel 1, the background display portion on the rear sidethereof will be visible without being affected by the amount of lightthat passes through the liquid crystal panel 1. The background displayportion could also be configured of means for self-generating light froman electrical supply, such as an LED.

This two-layer display type of electronic equipment is not limited to atimepiece; it can be applied to various other types of electronicequipment in which two-layer displays are necessary, in addition toportable electronic devices such as calculators, electronic notebooks,and wireless pagers.

Note that the method of driving the electrodes of the liquid crystalpanel 1 of the above embodiments is a static method, but the presentinvention is not limited thereto and a simple matrix method, amultiplexing method, or a thin-film transistor method could equally wellbe used therefor.

What is claimed is:
 1. A liquid crystal panel comprising: a firstsubstrate which is disposed on a side on which external light isincident and on which is formed at least one first electrode; a secondsubstrate which is disposed facing said first substrate and on which atleast one second electrode is formed; a liquid crystal layer which isinserted between opposing surfaces of said first and second substratesand which operates in a light-transmitting state and a light-scatteringstate, based on a voltage applied between said at least one firstelectrode and said at least one second electrode; and at least one,transparent layer disposed between said liquid crystal layer and said atleast one second electrode in a light-incident direction; wherein saidat least one transparent layer is formed of a material having arefractive index that differs from the refractive index of said at leastone second electrode.
 2. The liquid crystal panel as defined in claim 1,wherein when said liquid crystal layer has been set to saidlight-scattering state, the quantity of light scattered forward in saidlight-incident direction is greater than the quantity of light scatteredbackward against said light-incident direction.
 3. The liquid crystalpanel as defined in claim 2, wherein said liquid crystal layer is apolymer dispersed liquid crystal layer comprising liquid crystal andpolymers.
 4. The liquid crystal panel as defined in claim 1, whereinsaid at least one transparent layer is formed of a material selectedfrom glass, polymer films, transparent electrode materials, andinterference films.
 5. The liquid crystal panel as defined in claim 1,wherein said at least one transparent layer is formed to be in contactwith said second substrate.
 6. The liquid crystal panel as defined inclaim 5, wherein a first main surface of said at least one transparentlayer is formed to be in contact with a surface on the opposite side ofsaid second substrate from said opposing surface, wherein said at leastone transparent layer is formed of a material having a differentrefractive index from the refractive index of said second substrate. 7.The liquid crystal panel as defined in claim 6, wherein said at leastone transparent layer is formed of a material having a refractive indexlarger than the refractive index of said second substrate.
 8. The liquidcrystal panel as defined in claim 7, wherein a second main surface onthe opposite side from said first main surface of said at least onetransparent layer is formed to be in contact with an air layer; andwherein when the refractive index of said second substrate is n₀, therefractive index of said at least one transparent layer is n₁, and therefractive index of said air layer is n₂, the following relationship isestablished: n₂<n₀<n₁.
 9. The liquid crystal panel as defined in claim6, wherein said at least one second electrode is a transparentelectrode; and wherein said at least one transparent layer is formed ofthe same material as the transparent electrode material that forms saidat least one second electrode.
 10. The liquid crystal panel as definedin claim 9, wherein said at least one transparent layer and said atleast one second electrode are formed of tin oxide or indium tin oxide(ITO).
 11. The liquid crystal panel as defined in claim 1, wherein saidat least one transparent layer is formed on the opposite side of saidsecond substrate from said opposing surface, with an air layertherebetween, and said at least one transparent layer is formed of amaterial having a refractive index that differs from the refractiveindex of said air layer.
 12. The liquid crystal panel as defined inclaim 1, wherein said at least one transparent layer is formed betweensaid at least on second electrode and said second substrate, and isformed of a material having a refractive index different from therefractive indices of said at least one second electrode and said secondsubstrate.
 13. The liquid crystal panel as defined in claim 1, whereinsaid at least one transparent layer is formed on part of a flat surfaceregion facing said liquid crystal layer.
 14. The liquid crystal panel asdefined in claim 1, wherein said at least one transparent layer isformed is formed of different materials having different refractiveindices, disposed in different locations within the same flat surfaceregion facing said liquid crystal layer.
 15. The liquid crystal panel asdefined in claim 1, wherein a plurality of said transparent layers arestacked, and adjacent transparent layers are formed of materials havingdifferent refractive indices.
 16. The liquid crystal panel as defined inclaim 15, wherein a number of said superimposed transparent layerswithin a region facing said liquid crystal layer differs with location.17. The liquid crystal panel as defined in claim 1, wherein first to Nth(where N≧2) of said transparent layers are stacked, and adjacenttransparent layers are formed of materials having different refractiveindices; wherein said first transparent layer located in a previousstage in said light-incident direction is formed to be in contact with asurface on the opposite side of said second substrate from said opposingsurface, and said Nth transparent layer is formed to be in contact withan air layer; and wherein the refractive indices of said first to Nthtransparent layers are set to increase in said light-incident direction.18. Electronic equipment comprising: a liquid crystal panel which isdisposed on a side on which external light is incident; and a backgrounddisplay portion which is forward of said liquid crystal panel withrespect to a light-incident direction; wherein said liquid crystal panelcomprises: a first substrate which is disposed on said side on whichexternal light is incident and on which at least one first electrode isformed; a second substrate which is disposed facing said first substrateand on which at least one second electrode is formed; a liquid crystallayer which is inserted between opposing surfaces of said first andsecond substrates and which is set to one of a light-transmitting stateand a light-scattering state, based on a voltage applied between said atleast one first electrode and said at least one second electrode, tomake said background display portion visible when in saidlight-transmitting state; and at least one transparent layer disposedbetween said at least one second electrode and said second substrate,wherein said at least one transparent layer is formed of a materialhaving a refractive index that differs from the refractive indices ofsaid at least one second electrode and said second substrate.
 19. Theelectronic equipment as defined in claim 18, wherein said backgrounddisplay portion comprises a light-reflecting portion of a lowbrightness.
 20. The electronic equipment as defined in claim 18, whereinsaid background display portion is an analog timepiece comprising a dialplate and an indicator means.
 21. The electronic equipment as defined inclaim 18, further comprising illumination means for illuminating saidbackground display portion.
 22. The electronic equipment as defined inclaim 18, wherein said background display portion comprises alight-emitting portion for emitting an optical pattern for a backgroundimage.
 23. The electronic equipment as defined in claim 22, wherein saidlight-emitting portion is a liquid crystal panel for a background imagedisplay having a backlight.
 24. The electronic equipment as defined inclaim 22, wherein said light-emitting portion comprises means forself-generating light from an electrical supply.
 25. A liquid crystalpanel comprising: a first substrate having an inner surface and an outersurface, said outer surface facing incident external light; at least onefirst electrode disposed on said first substrate; a second substratehaving an inner surface and an outer surface, said second substratebeing disposed such that said inner surface of said second substratefaces said inner surface of said first substrate; at least one secondelectrode disposed on said second substrate; a liquid crystal layerinterposed between said inner surfaces of said first and secondsubstrates, said liquid crystal being operable in a light-transmittingstate and a light-scattering state according to a voltage appliedbetween said first and second electrodes; and at least one transparentlayer disposed between said liquid crystal layer and said at least onesecond electrode, said at least one transparent layer having arefractive index different from a refractive index of an opticallytransmissive medium adjacent said at least one transparent layer. 26.The liquid crystal panel of claim 25 wherein said at least onetransparent layer is selected from the group including glass, polymerfilms, transparent electrode materials, and interference films.
 27. Theliquid crystal panel of claim 25 wherein said at least one transparentlayer is disposed adjacent said outer surface of said second substrate.28. The liquid crystal panel of claim 27 wherein a layer of air isinterposed between said at least one transparent layer and said outersurface of said second substrate.
 29. The liquid crystal panel of claim25 wherein said at least one transparent layer comprises a plurality ofmaterials having a plurality of refractive indices.
 30. The liquidcrystal panel of claim 29 wherein at least some of said plurality ofmaterials are co-planar.
 31. The liquid crystal panel of claim 29wherein at least some of said plurality of materials are stacked.
 32. Aliquid crystal panel comprising: a first substrate which is disposed ona side on which external light is incident and on which is formed atleast one first electrode; a second substrate which is disposed facingsaid first substrate and on which at least one second electrode isformed; a liquid crystal layer which is inserted between opposingsurfaces of said first and second substrates and which operates in alight-transmitting state and a light-scattering state, based on avoltage applied between said at least one first electrode and said atleast one second electrode; and at least one transparent layer disposedforward of said liquid crystal layer in a light-incident direction;wherein said at least one transparent layer is formed of differentmaterials having different refractive indices, disposed in differentlocations within the same flat region facing said liquid crystal layer.33. A liquid crystal panel comprising: a first substrate which isdisposed on a side on which external light is incident and on which isformed at least one first electrode; a second substrate which isdisposed facing said first substrate and on which at least one secondelectrode is formed; a liquid crystal layer which is inserted betweenopposing surfaces of said first and second substrates and which operatesin a light-transmitting state and a light-scattering state, based on avoltage applied between said at least one first electrode and said atleast one second electrode; and a plurality of transparent layersdisposed forward of said liquid crystal layer in a light-incidentdirection, the plurality of transparent layers being stacked, andadjacent transparent layers being formed of materials having differentrefractive indices, wherein a number of said superimposed transparentlayers within a region facing said liquid crystal layer differs withlocation.